Anja Henß oral presentation (OB4-Fri1-1-5)
2D and 3D analysis of bone cells using the delayed extraction mode
1 Justus-Liebig University, Heinrich-Buff-Ring 17, 35392 Gießen, Germany
2 Justus-Liebig University, Frankfurter Str. 98, 35392 Gießen, Germany
3 Justus-Liebig University, Aulweg 128, 35392 Gießen, Germany
4 Technical University Dresden, Budapester-Straße, 01062 Dresden, Germany
Beside conventional applied methods like light- and electron-microscopy also mass spectrometry imaging becomes increasingly important for cellular analyses as it offers specific chemical information as part of the image. Among mass spectrometry imaging (MSI) methods like MALDI and DESI, ToF-SIMS provides the best lateral resolution and the delayed extraction of the secondary ions further improves the achievable lateral resolution down to 100 nm.  This makes ToF-SIMS to a very potential candidate for cellular analyses, only exceeded by NanoSIMS, that comes along with an outstanding lateral resolution of 50 nm but is limited by the number of simultaneously detectable elemental masses. Therefore, ToF-SIMS is the more versatile technique, which combines a broad mass range with a high lateral resolution and the possibility of 3D analysis.
Within our project we take advantage of the delayed extraction mode for the analyses of bone cells in vitro and in vivo from healthy and diseased donors and their interaction with regenerative biomaterials. We demonstrate that hMSCs, which have been cultured on a silica based composite material, show clearly an increased amount of Silicate inside the cells. By detection of those intracellular particles the hypotheses is supported, that not only Calcium but also Silicate mediates the osteogenic behaviour of the cells. However, the uptake and molecular mechanisms remain to be elucidated. Regarding bone diseases like osteoporosis osteocytes seem to play an important role although sparse information is available so far. Osteocytes can be found in mature bone, are stellate shaped and form a network via canaliculi. Osteocytes act like mechanosensors and transmit signals over long distances. In diseased bone they degenerate and change their morphology. Using ToF-SIMS we analyse the mineralisation and collagen structure of the osteocytes to reveal the degeneration process. The challenge here is to localise the osteocytes and to identify promising candidates for analysis as well as to resolve the small structures. With depth profiling and delayed extraction we study bone cells which have been grown in the presence of nanoparticles. Doing so we obtain high resolution images and 3D reconstructions and can unambiguously identify and localize the nanoparticles inside the cells. The nanoparticles are used as antibacterial coatings for implants to prevent infections although their effect on cells is still under investigation.
1. Vanbellingen, Q.P., et al., Rapid Communications in Mass Spectrometry, 2015.
2. Wagner, A., et al., Biomedical materials, 2017.
3. Jilka, R.L. and C.A. O’Brien, Current Osteoporosis Reports, 2016. 14